Acetaldehyde → Tert-butyl 8-ethyl-9-phenyl-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate

Participants

Reaction Steps

To a solution of tert-butyl 9-phenyl-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate (336 mg, 1.01 mmol) in ethanol (3 mL) was added acetaldehyde (62 μL, 1.11 mmol) then sodium cyanoborohydride (89 mg, 1.42 mmol) and the reaction mixture was stirred for 2 hours. The reaction mixture was concentrated in vacuo, partitioned between DCM (50 mL) and 1:1 aq. sat. NaHCO3/25% NaOH (10 mL), and the aqueous layer was further extracted with DCM (2×25 mL). The combined organics were dried with MgSO4 and concentrated in vacuo to give tert-butyl 8-ethyl-9-phenyl-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate (298 mg, 82%). ESI-MS m/z calc. 360.5. found 361.7 (M+1)+; Retention time: 1.30 minutes (3 min run).

Provenance & Evidence